Mixing valves having valve bodies configured to combine flaws of hot and cold fluids to provide mixed fluids having a controlled temperature are described in disclosures of patent specifications such as International Patent Application No. PCT/US02/27056 published as WO 03/019315.
In hydronic heating systems the role of a water temperature regulating valve is to: (1) receive high temperature water from a boiler or similar heat source; (2) receive lower temperature water returning from the heating loops of the hydronic heating system; (3) output water at a constant temperature to the heating loops of the hydronic heating system by regulating the relative flow rates of the high and lower temperature water through the valve; and (4) ensuring that any additional water added to the hydronic heating system from the boiler or similar heat source is replaced by a corresponding amount of water being returned to the boiler or similar heat source (a requirement arising from the fact that the output water is going to a closed loop which returns the water temperature regulating valve). Additionally it is important that the water temperature regulating valve provide overall temperature control to the hydronic heating system so as prevent damage to floor structures or floor coverings.
Regulation of the water temperature is achieved by a mechanism commonly used in tempering valves and thermostatic devices.
Generally, in these types of valves, the required flow passages to direct the high temperature water and lower temperature water to regulating gaps are formed by cast or mechanical channels within a brass valve body.